Making a Smooth Oval
It might be easier to construct your track as a curve, and adjust the camber before converting it to a mesh.
Create 2 curves, one your track path, and another for the road surface. In the path, make sure there are control points at the apex of curves you wil need to camber.

In the path's Data tab, you can adjust assign the road surface as the path's Bevel Object, and the U resolution to give you reasonably smooth curvature (you might want to leave yourself room in the resolution for subdivision,later)

Under proportional editing, you can CtrlT adjust the tilt of the curve at the points you want cambered. You can even AltS adjust the width of the track in places, if you want to.

When you're done, you can convert to a mesh, do whatever else you need to, and maybe subdivide for smoothness. Here, the perimeter has been extruded down in Z, for embedding in a landscape, but that would all depend on how you're constructing your scene.
I did find a bug while trialling this answer.. my curve was cyclic, and I had proportional editing set to 'Connected'. The Proportional Edit did not cross over the first-and-last control point on the curve, treating one side as if it was not connected. A get-around would be to split the curve, and rejoin it in a place that doesn't matter so much.